Currently, photolytic and photovoltaic power sources only utilize that portion of the solar spectrum that contains photons having energy greater than or equal to the energy threshold required to activate the photovoltaic or photolytic process. Lower energy photons, that is, photons with energy lower than the threshold required to activate the photovoltaic or photolytic process, are currently wasted.
Similarly, solar pumping of a laser gain media also typically only uses that portion of the solar spectrum that contains photons having energy greater than or equal to the absorption threshold. Lower energy photons, that is, photons with energy lower than the absorption threshold, likewise are currently wasted.